While it appeared safe to discontinue prophylaxis with CD4 count between 101–200 cells/μL, the upper confidence interval level of the incidence rate in persons who discontinued prophylaxis with CD4 count ≤100 cells/μL after initiating HAART was high (9.83 events per 100 PYFU), suggesting an unacceptably high risk of PCP in this one study. The gene discussed is CD4; the disease is pneumocystosis.